Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
  • F42B10/00—Means for influencing, e.g. improving, the aerodynamic properties of projectiles or missiles; Arrangements on projectiles or missiles for stabilising, steering, range-reducing, range-increasing or fall-retarding
  • F42B10/60—Steering arrangements
  • F42B10/62—Steering by movement of flight surfaces
  • F42B10/64—Steering by movement of flight surfaces of fins
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
  • F42B10/00—Means for influencing, e.g. improving, the aerodynamic properties of projectiles or missiles; Arrangements on projectiles or missiles for stabilising, steering, range-reducing, range-increasing or fall-retarding
  • F42B10/60—Steering arrangements
  • F42B10/66—Steering by varying intensity or direction of thrust
  • F42B10/668—Injection of a fluid, e.g. a propellant, into the gas shear in a nozzle or in the boundary layer at the outer surface of a missile, e.g. to create a shock wave in a supersonic flow

Definitions

• CAS command authority to maneuver a flight vehicle over an entire vehicle speed range encompassing both the subsonic and supersonic Mach numbers and within the atmosphere and e ⁇ o-atmosphere
• Flight vehicles such as self-propelled missiles, gun or tube launched guided projectiles, kinetic interceptors and unmanned aerial vehicles require command authority to maneuver the vehicle to perform guidance and attitude control
• Each of these vehicles may operate over a speed range encompassing both subsonic and supersonic Mach numbers and within the atmosphere and e. ⁇ o-atmosphere during a single mission
• the differing speed and atmospheric conditions present different problems for effectively maneuvering the vehicle under volume, weight and cost constraints imposed by the vehicle and mission
• CAS Control Actuation System
• the CAS employs a set of four fin control surfaces actuated by individual servo motors Actuation of the fin control surfaces into the onrushing free stream produces drag and directional forces to maneuver the vehicle Control surfaces are effective at supersonic speeds above Mach 1 in atmosphere where sufficient drag and force is produced to quickly maneuver the vehicle
• the amount of drag and force is relatively small and maneuverability is limited
• actuation of the fin control surface is wholly ineffective because no drag or force is produced
• the servo motors are very expensive, up to 25% of the missile cost, and have reliability issues related to the moving parts of the servo motor being exposed to very high g loads at launch
• a liquid-fuel divert thruster system includes one or more liquid or gas storage tanks and a regulator valve to mix and a combustion chamber to burn the liquid or gas propellants
• the liquid propellant configurations are comprised of either monopropellant systems or bipropellant systems where the bipropellant system contains a fuel and an oxidizer Liquid-fuel has the advantage that the amount of thrust can be continuously varied, started and stopped, and may be less expensive than servo motors
• these systems are large and heavy Liquid propellant di ⁇ ert thruster systems are used in space-based platforms such as satellites and kinetic kill- vehicles
• a solid-fuel propellant system is more light weight and less complicated but once ignited burns until completion where all the solid fuel has been consumed
• a variant on the solid-fuel propellant system are "'pyrotechnic thrusters" or "'poppers' " that generate a thrust pulse Pyrotechnic thrusters can be effectively
• the liquid or solid-fuel propellant divert thrusters are not as effective as control surfaces such as fins at supersonic speeds in atmosphere
• the on rushing high speed free stream relative to the vehicle has such a high degree of momentum in conjunction with the high vehicle momentum that the divert jet thrust is onl> marginally effective unless unrealistically large divert thrusters are employed
• a divert thruster system would have to burn for a long time in order to maneuver Long burn times at supersonic speeds create a vehicle packaging problem because of the volume requirements imposed by the amount of propellant required
• the ability of the vehicle to maneuver quickly which is critical in many military applications, is also limited at supersonic speeds SUMMARY OF THE INVENTION
• the present invention provides a solid-fuel pellet thrust and control actuation system for maneuvering flight vehicles over subsonic and supersonic speeds at flight conditions within the atmosphere and also exo-atmosphere Command authority at supersonic speeds in atmosphere is accomplished by providing an airframe having a pivotable aerodynamic control surface that is recessed within the airframe and a cavity there between One or more solid-fuel pellets are ignited to expel gas that flows into the cavity creating a cavity pressure that overcomes the external pressure forcing the control surface to deploy The resulting drag and force maneuver the airframe
• the flow of pressurized gas from the cavity to the external environment is restricted to meet a deployment time objective
• the gas may be used to inflate an 'air bag' to deploy the control surface with the porosity of the fabric controlling the bleed of pressurized gas to the environment
• the control surface is formed with a through- hole above a throat in the airframe that together form a virtual converging/diverging nozzle
• the nozzle expels gas through the hole in the control surface at supersonic speed producing a divert thrust and force to maneuver the airframe without pressurizing the cavity to deploy the surface
• the nozzle expels gas that obstructs the free stream producing a shock that in turn restricts gas flow from the nozzle directing at least a portion of the gas into the cavity to pressurize the cavity and actuate the control surface
• command authority is a combination of divert thrust and surface deployment At a certain supersonic Mach number (M>1 ) substantially all of the gas is diverted into the cavity so that command authority is effectively only the deployment of the aero surface
• the solid-fuel pellet thrust and CAS functions as a divert or attitude thruster
• the free stream essentially plugs the nozzle so that the solid-fuel pellet thrust and CAS functions to deploy the aerodynamic control surface
• the solid-fuel pellet thrust and CAS provides the capability to operate over subsonic and supersonic speeds and within atmosphere and exo-atmosphere and deploys the most efficient means of maneuvering the flight vehicle depending on the operating regime
• FIG 1 is a diagram of a flight vehicle having a set of hinged aero control surfaces for providing command authority to maneuver the vehicle.
• FIG 2 is an enlarged view of the tail section illustrating an embodiment of solid-fuel pellet CAS
• FIGs 3a and 3b are an exploded view of a control surface assembly and an enlarged view of the tail section illustrating the deployed surface
• FIG 4 is a diagram of an ignition system for firing the solid-fuel pellets.
• FIG 5 is a diagram illustrating the pressu ⁇ zation of the cavity and controlled bleed of high pressure gas from the cavity to the external environment to control surface deployment,
• FIGs 6a and 6b are diagrams of an alternate embodiment of a solid-fuel pellet CAS
• FIGs 7a through 7c are different views of an alternate embodiment of the thrust and CAS providing both divert thrust and control of the aero control surface
• FIG 8 is a diagram illustrating operation of the CAS at subsonic speeds in Earth atmosphere or at any speed outside Earth atmosphere
• FIGs 9a-9b are diagrams illustrating operation of the CAS at supersonic 5 speeds in Earth atmosphere.
• FIG 10 is a diagram of nozzle exit and free stream total pressure dependence on nozzle exit and free stream Mach number
• FIG 1 1 is a diagram of nozzle exit and free stream momentum dependence on nozzle exit and free stream Mach number.
• FIGs 12a and 12b are diagrams of a typical atmospheric and exo-atmosphe ⁇ c flight sequences.
• FIG 13 is a diagram of the aero control surface including a roll control port
• FIG 14 is a diagram of a flight vehicle having an opposing pair of deployed aero control surfaces for providing roll control to maneuver the vehicle
• the present invention provides a solid-fuel pellet thrust and control actuation system for maneuvering flight vehicles over subsonic and supersonic speeds and within the atmosphere and e ⁇ o-atmosphere
• the system is compact, lightweight, inexpensive and reliable in that it requires no moving parts other than the aerodynamic control surface
• the described system is generally applicable to a wide
• a base embodiment ot a pellet control actuation system or 'P-CAS' uses solid-fuel pellets to actuate a control surface with particular effectiveness in the supersonic regime within atmosphere
• Another embodiment of a pellet thrust and control actuation system or 'PT-CAS' adds a virtual converging/diverging nozzle formed b ⁇ a 0 through-hole in the control surface and a throat to the gas chamber to provide additional divert thrust capability for improved maneuverability at subsonic speeds in atmosphere or at any speed in the e ⁇ o-atmosphere
• Roll control functionality can be provided in either the base P-CAS or more advanced PT-CAS embodiments by locating a roll control port on the side of the aerodynamic control surface Gas 5 flowing through this port creates a force on the vehicle circumferential direction, resulting in the vehicle rotating (rolling) about its longitudinal axis I hese ports are located on alternate sides of consecutive control surfaces
• a flight vehicle 10 such as a missile includes a set of four aerodynamic control surfaces 12 commonly referred to as fins, flaps or canards 0 pivotably mounted on an airframe 13
• a through-hole 14 formed in a fore section of surface 12 forms a portion of a virtual converging/diverging nozzle
• a CAS ignites solid-fuel pellets to produce a gas stream
• This gas stream is either expelled from through-hole 14 at supersonic speeds to produce a divert thrust to maneuver the airframc or is directed into a cavity between an aft section of the control surface and the airframe to pressurize the cavity and actuate the control surface 12 to maneuver the airframe
• the gas stream is expelled from the nozzle with little or no resistance from the on rushing free stream 16 to produce the divert thrust
• the control surface remains recessed within the airframe At supersonic speeds in atmosphere, the interaction of the expelled gas and the free stream 16 produces
• Aerodynamic control surface 12 on airframe 13 is pivotable about a pivot point 18 between a retracted position out of the free stream 16 and deployed positions in the free stream to provide drag to maneuver the airframe
• the control surface may be hinged or flexed to pivot about the point
• a cavity 19 is positioned aft of the pivot point between an aft section 20 of the control surface and airframe 13
• the cavity is formed by a recess 22 in the surface of airframe 13
• the cavity may be formed by a recess in the aft section of the control surface or a combination of the two recesses
• a chamber 24 including one or more propellant chambers 26 each holding one or more solid-fuel pellets 28 is disposed inside the airframe
• a throat 30 couples the chamber to the cavity'
• An ignition system 32 ignites the solid-fuel pellets in one or more propellant chambers to expel gas 34 that flows through the throat into the cavity to pressurize the cavity and deploy the control surface
• the cavity could extend the length of the surface Limiting the cavity to an aft section of the surface provides for better propellant gas utilization and increased efficiency
• the ignition system includes an 'electric match' 36 coupled to each propellant chamber and wires 38 connected to a controller 40
• Electric match 36 may be a small charge of flammable material that, when burned, releases a predetermined amount of hot combustion gases sufficient to ignite the pellets
• the combustion of the igniter may be initiated, for example, by an electric current flowing through a heater wire adjacent to, or embedded in.
• Each solid fuel pellet may be composed of at least some of an energetic fuel material and an oxidizer material
• Each fuel pellet may contain additional binder and/or plasticizer material
• the binder material and the plasticizer material may be reactive and may serve as a fuel material and/or an oxidizer material Suitable compositions for gas generator solid fuel pellets are well known
• the solid-fuel pellets are suitably formed from guanidine (or guanidinium) nitrate and basic copper nitrate, cobalt nitrate, and combinations thereof, as described in U S Patent 5.608, 183 At least 60% of the total mass of the fuel pellets may be composed of guanidine nitrate and basic copper nitrate
• the solid fuel pellets may have relatively low combustion temperatures
• a rest ⁇ ctor mechanism 42 is provided to control the bleed of exhaust gas 44 from the ⁇ .avity to the external environment to achieve a deployment time.
• the restrictor mechanism is needed to allow the cavity to be pressurized to deploy the control surface and to depressu ⁇ ze the cavity to allow the surface to be retracted If gas flow from the cavity to the external environment were not restricted at all the gas would simply vent to the external environment and the cavity would not pressure Conversely if gas flow was completely restricted the cavity would not depressu ⁇ zc
• the rate at which gas is bled out of the cav ⁇ t> can be constant or variable with cavity pressure or deployment angle to achieve the deployment time objective
• the restrictor mechanism 42 includes side panels 46 and an endplate 48 having vent holes or slots 50 formed therein
• Side panels 46 are disposed on opposite sides of aero control surface 12 longitudinally from the pivot point to the aft end of the surface In the retracted surface position, the side panels are recessed inside the airframe When the control surface is actuated to a deployed position, the side panels still overlap the airframe to prevent exhaust gas from escaping as best shown in Figure 3b
• Typical deployment angles are fairly small in many flight vehicles, approximately 5- 15° Endplate 48 is disposed on the aft end of the control surface and is recessed within the airframe when the surface is in its retracted position
• vents 48 rise above the surface of the airframe pro ⁇ iding passageways from cavity 19 to the external environment
• the pressurized gas in the cavitv bleeds through the vents to the external environment at a controlled rate
• the pattern of vents may be configured to provide a uniform or variable bleed rate
• free stream 16 flows over the airframe at supersonic speeds (Mach > I) with a leading free stream static pressure Pl
• the ignition s>stem ignites one or more solid-fuel pellets to expel gas 34 that flows through the throat into the cavity creating an aggregate cavity pressure P3 that forces the control surface to actuate to a deployed position
• Deployment of the control surface into the supersonic free stream 16 produces a shock 52.
• the pressure P2 downstream of the shock is the external free stream aggregate pressure on the exterior of the control surface
• the aggregate pressure is the exterior or cavity pressure averaged over the surface to compensate for any local variations
• P3 > P2 the control surface is actuated to a deployed position
• the control surface in atmosphere produces a drag force, which in turn produces a force 55 which is normal to the vehicle longitudinal a ⁇ s to maneuver the airframe
• the exhaust gas 44 flows through the vents to the external environment
• the forcing function produced by igniting the solid-fuel pellets is strong and fast causing the control surface to move to the desired deployed position rapidly
• the external free stream aggregate pressure will force the control surface, against the resistance of the rest ⁇ ctor mechanism to bleed the exhaust gas to the external environment, back to its recessed position
• the control surface may be actuated to
• the controller 40 decides when to fire one or more propellant chambers to actuate the control surface to maneuver the flight vehicle
• the controller may operate "open-loop" generating the ignition sequence based on parameters such as the deployment angle, deployment time, vehicle air speed, vehicle altitude etc
• the controller uses these parameters to calculate or look-up (from a precalculated table) the desired ignition sequence
• This ignition sequence may compensate for such factors in the change in force on the control surface as it deploys and the change in volume, hence pressure of the cavity
• the controller may operate '"closed- loop" to modify the above ignition sequence based on one or more sensed parameters For example, sensors could be deployed on the airframe to measure the deployment angle of the surface or the cavity pressure in real-time and feed those parameters back to the controller The controller could than alter the ignition sequence to maintain the desired deployment angle for a specified time
• a fabric bag 60 is disposed in cavity 19 and coupled to throat 30 so that gas 34 inflates the bag to deploy the surface 12
• the porosity of the fabric forms the restrictor mechanism to control the bleed of exhaust gas 44 from the cavity
• the fabric may have a uniform porosity to bleed gas from both sides and the end Alternately the fabric may be more or only porous at the aft end 62 to bleed the exhaust gas to, for example, pressurize the base region of the flight vehicle
• This PT-CAS can provide effective maneuverability at subsonic speeds in atmosphere and at supersonic speeds in atmosphere I his embodiment effectively combines the functionality of both a divert thruster and a servo motor CAS and is less expensive For purposes of clarity and brevity but without loss of generality like numbers for elements in P-CAS 15 without divert thrust capability will be used for like elements in PT-CAS 70 with divert capability
• the only required modification to the base P-CAS embodiment to provide the additional divert thruster capability is the formation of through-hole 14 in aero control surface 12 above throat 30 to form ⁇ irtual converging/diverging nozzle 72
• the through-hole has a larger diameter than the throat
• the cavity 19 propellant chambers 26.
• ignition system 32, rest ⁇ ctor mechanism 46 and controller 40 are functionally the same
• the specific design of each component will vary with application and mission requirements e g total propellant required, deployment time objective, etc
• the requirements on the throat are relaxed in the base embodiment
• the throat need only direct the combusted gas to the cavity and not form a nozzle that provides a supersonic transition to the expelled gas
• command authority is a combination of divert thrust and actuation of the control surface
• the Mach numbers at which the transition region starts and stops depend on a number of design and mission parameters
• the controller may operate in either open or closed-loop configurations in either the transition or supersonic regions depending on mission requirements
• Figures I O and 1 1 are plots of nozzle exit and free stream total pressure and momentum versus nozzle exit and free stream Mach number, respectively These plots illustrate the dynamics of divert thrust and control surface as vehicle velocity increases and provide insight into the design space for the solid-fuel pellet CAS with a virtual converging/diverging nozzle
• the pellet chamber generates a chamber pressure of about 100 psia with a nozzle exit Mach number of about 2 0
• the nozzle exit pressure 90, free stream total pressure 92 and free stream Pitot pressure 94 that govern how the divert gas jet transitions from divert control authority to control surface control authority are shown in Figure 10
• the gas from the divert jet flows freely into the freestream and does not generate a shock either on the control surface or near the nozzle exit plane
• the area of the hole on the control surface external surface forms part of the nozzle
• the divert jet gas causes an obstruction to the free stream which in turn results in generation of a shock initially at the hole in the control
• the free stream total pressure 92 represents the maximum pressure that the free stream can possibly attain
• the free stream Pitot pressure 94 is the pressure downstream of a normal shock This represents the lowest possible pressure that the free stream can attain
• the actual aggregate external pressure P2 on the control surface will depend on the strength of the shock pattern and will lie somewhere between the Pitot pressure 94 and the total pressure 92
• I he area of through-hole 14 which forms part of the nozzle, and the area created in the cavity at the aft end of the control surface as it deploys must be controlled so that the pressure P3 is greater than the pressure P2 for the required time as determined by the guidance requirements If the pressure P3 is not high enough, the control surface will not deploy
• the through-hole inlet geometry and it's location in the control surface must be precisely controlled to maintain the required pressure (P3) in the cavity so that the control surface functions as required for the time required
• the nozzle exit momentum 90 and the free stream momentum 92 are shown in Figure 1 1 for the same chamber condition ( 100 psia) and nozzle geometry (exit Mach number 2 0)
• the nozzle exit momentum is substantially larger than the free stream momentum the gas jet from the divert nozzle will flow into the external stream with ease
• the free stream momentum increases
• the free stream momentum is substantially larger than the nozzle exit plane momentum by a threshold amount, the gas from the nozzle will be almost completely restricted from flowing into the external stream and will be directed into the cavity
• the Mach number at which this occurs for the nozzle and chamber configuration selected in this example is about 2 65 (free stream momentum about 145 lb*force/ ⁇ n 2 and nozzle exit momentum of 120 lb*force/ ⁇ n 2 )
• the parameters that effect control surface deployment are through-hole geometry, cavity pressure, free stream Mach number, pellet motor chamber pressure and pellet motor nozzle geometry
• the control surface is through-hole geometry, cavity pressure, free stream Mach number, pellet motor chamber pressure and pellet motor nozzle geometry
• Exemplary command authority time lines 100 and 102 using the solid-pellet propellant CAS with the virtual converging/diverging nozzle for atmospheric and exo- atmosphe ⁇ c flight to provide guidance of the vehicle to its intended target are illustrated in Figures 12a and 12b, respectively.
• command authority is obtained by firing propellant chambers to produce only a divert thruster
• command authority gradually transitions to use of the control In this transition region, firing propellant chambers produces a combination of divert thrust and control surface drag
• command authority is achieved by firing propellant chamber to pressurize the cavity and actuate the control surface
• command authority is obtained by the use of the divert thruster As the vehicle speed increases to Mach 1 and greater from time “3" to '"4". command authority transitions to use of the flap During atmospheric cruise or acceleration from time "4" to "5" command authority is achieved by use of the control surface Upon attaining an altitude where the ambient density is very low (e ⁇ o- atmosphere).
• Roll control functionality can be provided in either the base P-CAS or more advanced PT-CAS embodiments by locating a roll control port 1 10 on the side of the aerodynamic control surface 12 as shown in Figures 13 and 14 Gas flowing through this port creates a force 112 on the vehicle circumferential direction (tangential to the surface of the airframe). resulting in the vehicle rotating (rolling) 114 about its longitudinal axis 116 to produce or negate roll
• These ports are located on alternate sides of consecutive control surfaces

Landscapes

• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
• Toys (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=41264078

Family Applications (1)

Country Status (4)

Families Citing this family (11)

Family Cites Families (34)

• 2008
  • 2008-09-03 US US12/203,302 patent/US8193476B2/en active Active
• 2009
  • 2009-04-21 AT AT09763088T patent/ATE543074T1/de active
  • 2009-04-21 EP EP09763088A patent/EP2297543B1/de active Active
  • 2009-04-21 WO PCT/US2009/041240 patent/WO2009151796A2/en not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events